Low intensity, infrared radiant heating systems are preferred over forced air and hot water systems, for example, in many applications. This preference is due in large part to the fact that radiant heating involves direct energy conversion; building mass (concrete floors, machinery, et cetera), persons, plants and animals in the heated areas receive sensible heat via direct energy absorption rather than through the movement of air which has been heated. As a result, people can work comfortably in areas where the actual air temperature is lower than that required for comfort in forced air and convection systems; this, of course, gives rise to substantial energy savings. In addition, a concrete floor under an infrared emitter will absorb energy in the range of frequencies characteristic of radiant tube systems and will thereafter release thermal energy through reradiation to make the enclosure more comfortable for its inhabitants on an economical basis. Such reradiation from the floor warms the feet of the persons working or living in the effected area not only during heating system operation but more importantly afterwards, as well. Infrared systems have the further advantage in greenhouses and the like by positively effecting plant growth rate.
Low intensity infrared systems have further advantages in high directionality capabilities obtainable through the use of reflectors which aim the radiant energy where it is needed the most, thus increasing the effective utilization of the available energy.
A fuel-fired, low intensity radiant energy heating system typically includes a metal tube infrared emitter, the tube being charged with hot gaseous effluent by means of a fuel-fired heated. The system is usually installed with the emitter tube positioned 7 to 50 feet above floor level. Reflectors in the form of light gauge metal fabrications or stampings are installed immediately above the emitter tube over substantially the entire operating length thereof to direct the emitted radiation toward the floor. Typically the entire structure, including the tube, is held together by means of an alloy steel wire hanger which is bent to provide seats for receiving the opposite edges of the reflector. The center portion of the hanger is curved to receive the tube. Wire hangers are placed at regularly spaced intervals along the longitudinal run of the reflector assembly. The alloy steel wire hangers are then connected at their top portions to an overhead structure, such as a ceiling beam or other support, by a chain fastened to the support and, in turn, fastened to the hanger. The alloy steel wire hanger is, essentially, custom bent, resulting in non-uniformity among hangers and increased cost of manufacture.
Convection currents caused by temperature differences along the length of the emitter tube and disturbances within the enclosure actually scrub heat off the emitter tube as the convection current flows from the burner end of the emitter tube to the effluent discharge end. This convection current allows heat to flow along the length of the tube until it reaches the end of the tube where the heat is discharged. This flow of heat along the tube results in a loss of directable radiant heat energy in the needed areas; requiring an increased output by the burner to compensate for the loss. Therefore if the amount of convected heat loss can be reduced, the fuel savings is increased, thus decreasing the operating cost of the system during operation.